Preparation and activity evaluation of relative p-n junction photocatalyst Co-TiO2/TiO2

Co-TiO2 photocatalyst was prepared by a sol-gel method using Co(NO3)(2) center dot A 6H(2)O and tetrabutyl titanate [Ti(OC4H9)(4)] as raw materials, and Co-TiO2/TiO2 photocatalyst was synthesized by mixing the Co-TiO2 sol with TiO2 sol. The Co-TiO2/TiO2 was characterized by X-ray powder diffraction, UV-Vis diffuse reflection spectrum, scanning electron microscopy, transmission electron microscopy, fluorescence spectra and X-ray photoelectron spectroscopy. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic reduction of Cr2O7 (2-) and photocatalytic oxidation of methyl orange under UV irradiation. The results showed that, for the photocatalytic reduction of Cr2O7 (2-), the optimum percentage of Co-doped for the Co-TiO2 was 0.5% (mole ratio of Co/Ti), and the optimum percentage of Co-TiO2 for the Co-TiO2/TiO2 was 2.0% (mole ratio of Co-TiO2/TiO2). The photocatalytic reduction activities of the Co-TiO2/TiO2 and Co-TiO2 are much higher than that of TiO2. However, the photocatalytic oxidation activities of the Co-TiO2/TiO2 and Co-TiO2 are much lower than that of TiO2. Effects of heat treatment on the photocatalytic activities of the Co-TiO2/TiO2 and Co-TiO2 were investigated. The mechanisms of influence on the photocatalytic activity were also discussed.